Alcohol, tobacco, and marijuana are the most commonly used substances among women of childbearing age, and use of these substances during pregnancy results in significant morbidities for both women and infants. The damaging fetal consequences of alcohol and tobacco are well-known, and newer research documents the harmful effects (e.g., increased infant mortality) of prenatal marijuana use. This is particularly alarming as marijuana use is on the rise. As many women use these substances unaware of their pregnancy, intervention during the preconception period is critical for preventing substance-exposed pregnancies (SEP). SEPs are heavily concentrated in women with lower financial resources, and services to address these issues with women of childbearing age are lacking. Primary care settings afford an opportunity to engage this hard-to-reach population and address interrelated problems, including substance abuse, ineffective contraception and HIV-risk behaviors. Face-to-face interventions involving sensitive information (e.g., substance use and sexual behaviors) may limit disclosure and draw resources from busy practices. Even more importantly, recent research indicates that disclosure of substance use, particularly marijuana, is improved with computer-based vs. face-to-face interventions. Thus, innovative and cost-effective methods that can be easily integrated to real-world medical settings are needed. Self-guided, computer-based interventions could improve disclosure and be more effective and efficient. Our previous work on brief motivational interventions to prevent alcohol- and tobacco-exposed pregnancies has yielded favorable results, yet marijuana use at follow-up was consistently associated with significantly poorer intervention outcomes. Therefore, preconception marijuana use needs to be addressed for maximal SEP reduction. This timely and practical randomized controlled study of 360 women of childbearing age within a primary care setting will compare the efficacy of the Choices4Health intervention delivered by a computerized tablet, the Choices4Health intervention delivered by a counselor and Brief Advice; all with the goal of reducing SEP (drinking below risk levels, tobacco cessation, marijuana cessation, and/or effective contraception use). Secondary outcomes include HIV-risk reduction and cost effectiveness. We believe this work is aligned with the need to offer effective and efficient substance use screening and treatment in front- line medical settings and will have significant impact on current standards of preconception care.